For many years, there has been a real interest in two different but related needs with respect to the telephone system. One has been for the telephone operating company to monitor the quality of telephone service from both the equipment and personnel standpoint. This has given rise to a number of systems for unobtrusively monitoring a line which is not in service by effectively seizing the line, placing test signals on the line and monitoring their quality. Other systems operate with the line in an OFF-HOOK condition, similarly placing a test signal on the line and monitoring its quality. In the case of personnel performance monitoring, conformance with established procedures and policies by operating personnel can be evaluated. Both of these monitoring type systems seek to remain unobstrusive so as to avoid interference with normal usage of the line or the privacy of the customer or employee.
More recently, systems have been developed for observing the quality of telephone service which includes a system for monitoring a large number of lines and for detecting when they go into use, to discriminate between incoming or outgoing calls and for recording data related to the line including elapsed time for various uses. Such a system is present in U.S. Pat. No. 3,917,915 to E. C. Karras.
A further refinement in telephone service monitoring apparatus is disclosed in U.S. Pat. No. 3,571,531 to H. Rubin et al. In this system, a monitor station includes a voice frequency monitoring headset, an alpha numeric printer, display lamps and is associated with a touch tone signal receiver register and translator for determining numbers dialed. The system responds to either an originating call or a terminating call (outgoing or incoming).
A related type of system involves the need to utilize the existing telephone system as an alarm reporting system, either manually or automatically.
The desirability of combining an alarm system with a telephone system has been recognized from the early days of the telephone. By 1940, technology had reached the level of producing an alarm system which upon a door opening condition is sensed and through a relay system is indicated as an alarm condition at a central operator station. Alarm recording apparatus allowed the identification of the reporting station. Such a system is disclosed in U.S. Pat. No. 2,195,627 to C. E. Lomax et al.
One sophisticated combined telephone and alarm system is disclosed in U.S. Pat. No. 4,273,960 to R. J. Fahey in which the system determines the status of the telephone line, either ON-HOOK or OFF-HOOK, and employing a timer, monitors activity of a living space. Non-activity such as non-use of the telephone or non-movement for preselected time periods is considered as an alarm condition and alerts an alarm monitoring station. Use of the telephone resets the timer. The U.S. Pat. No. 4,273,960 incorporates by reference portions of the disclosure of U.S. Pat. No. 4,259,548 of R. J. Fahey et al and discusses previous U.S. Pat. Nos. 3,885,235, 3,989,900, 4,121,160 and 4,134,108 having related features, all suitable for health care facilities when non invasive monitoring of resident's activity is desired for the resident's own well being.
These systems have not usually be considered related, however, they employ the tip and ring connections to a subscriber station to provide a non interfering subscriber status information channel. Each of these systems have been configured to fill the specific objective of the designer and lack the versatility of allowing the system user to configure the system to future needs or to allow system operation to be totally changed via software changes.